Erucamide-free closure and liner compositions

ABSTRACT

An exemplary erucamide-free composition for making container closures or closure sealants includes a matrix polymer, a silicone lubricant such as poly(dimethyl) siloxane, and a slip aid comprising a saturated amide, oxidized polyethylene, or combination thereof.

FIELD OF THE INVENTION

The present invention relates to compositions for making closures andclosure liners, and more particularly to compositions that are free oferucamide.

BACKGROUND OF THE INVENTION

It is known to make container closures and closure sealants usingpolymers with erucamide as a slip agent. However, erucamides areethylenically-unsaturated amides that react with ozone that is used forsterilization, thereby creating aldehyde off-tastes that adverselyaffect beverage products such as carbonated water and soft drinks.However, the use of saturated amides, such as behenamide, while avoidingthe off-taste problem, tend to be less effective as slip aids because itis believed that they migrate more slowly to the surface of the matrixpolymer and thereby are less efficacious in providing a low-frictionsurface.

As noted in World Patent WO 0236672A1 of Alphagary Corporation, it wasnoted that conventional closure sealants for beverage or food containershave utilized lubricants such as erucamide and oleamide, each of whichis conjugated. Because these lubricants are conjugated, they aresusceptible to photochemical breakdown and oxidative breakdown. In otherwords, oxidative breakdown of erucamide by ozone sterilization cancreate flavor-detracting contaminants such as ketones in addition toaldehydes. Ozone sterilization is frequently performed to sterilizebottled water products, such as mineral water and spring water. TheUnited States Food and Drug Administration requires ozone sterilizationfor sterilizing bottled water products manufactured and sold in theUnited States. Thus, there is a need for a closure sealant lubricantthat is resistant to oxidative breakdown from ozone sterilization.Additionally, there is a need for a closure sealant lubricant that isresistant to photochemiclal breakdown.

Thus, a novel erucamide-free composition is needed for making containerclosures and closure sealants.

SUMMARY OF THE INVENTION

In surmounting the problems noted above, the present invention providesa composition, suitable for container closures and closure sealants,comprising: (A) a matrix polymer, copolymer, or blend of polymer and/orcopolymers, which is essentially free of erucamide and which isessentially free of unsaturated amide; (B) a silicone lubricant havingan average molecular weight not less than 40,000 and being present in anamount not less than 0.01 parts and not greater than 10 parts based on100 parts of the base polymer(s); and (C) a slip aid comprising asaturated amide, an oxidized polyethylene, or mixture thereof; the slipaid being in an amount not less than 0.01 parts and not greater than 8parts based on 100 parts of the base polymers(s).

Polymers, copolymers, and blends thereof which are conventionally knownfor use as matrix polymers for closures and sealants are contemplatedfor use in the present invention.

The present invention is also directed to a lubricant/slip-aidcomposition for use in container closures and closure sealants. Anexemplary slip aid composition comprises: a silicone lubricant (e.g.,siloxane, organosiloxane) having an average molecular weight greaterthan 40000, the silicone being present in an amount of 0.01 parts—10parts based on 100 parts of matrix polymer(s) and a slip aid comprisinga saturated amide, an oxidized polyethylene, or mixture thereof.

Further advantages and features are described in further detailedhereinafter.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

As summarized above, exemplary compositions comprise a matrix polymerhaving essentially no erucamide or unsaturated amide; a siliconelubricant; and slip aid having a saturated amide, oxidized polyethylene,or mixture thereof.

The matrix polymer, copolymer, or blend thereof may be selected fromthose conventionally known for use in making containers, containerclosures, or closure sealants. For example, these include thermoplasticpolymers such as polyethylene or ethylene copolymer with other loweralkenes, polypropylene, thermoplastic rubbers, ethylene propylenecopolymers, acid modified ethylene propylene copolymers, styrenebutadiene rubber, carboxylated styrene butadiene block copolymer,polyisoprene, styrene isoprene styrene block copolymers, styrenebutadiene styrene block copolymers, styrene ethylene butylene styreneblock copolymers, polystyrene block polyethylene/propylene copolymers,polystyrene block polyethylene propylene polystyrene copolymers,polystyrene block polyethylene ethylene propylene styrene copolymerspolystyrene, ethylene vinyl acetate copolymers and terpolmers, ethyleneacrylate co and terpolymers ethylene vinyl alcohol copolymers, butylrubber, ethylene acid copolymers, and polyvinyl chloride polymers.

Compositions of the invention should be essentially free of erucamideand which is essentially free of unsaturated amide. In other words,amides contained in the composition should have an iodine value nogreater than 10 and more preferably no greater than 5. The iodine valueis a measure of the unsaturation of alkyl groups and can be measuredusing the Wjis procedure, such as ASTM D2075-92, among others.

Typical examples for closure liners are described in, for instance, U.S.Pat. No. 5,104,710, EP 0478109, EP 0599356, EP 0488491, and 0646158. Theliners may be applied to the closure in any of the known methods, suchas those described in, for example, U.S. Pat. No. 4,518,336, EP 207385,and U.S. Pat. No. 4,277,431.

Typical examples for closures are described in, for example, U.S. Pat.No. 5,045,594, U.S. Pat. No. 5,186,991, U.S. Pat. No. 6,399,170, WO0162837, EP 73334, and U.S. Pat. No. 4,462,502.

The addition of silicones to container closure and closure sealantcompositions are not new, and examples of can be found in EP 129309.However, they are used in conjunction with an unsatured amide(s) toprovide the ability to lessen removal torque.

In further embodiments of the invention, at least one siloxane may beused. For example, Japanese Patent Applicant No. 2000038495 described ahigh molecular weight siloxane as a slip aid in cap liners. However, thepresent inventors believe that the use of siloxanes alone areineffective at providing sufficient ability to reduce removal torque andfurthermore have the problem of polymer scuffing.

In further exemplary embodiments of the invention, a silicone can beused as a process aid. See e.g., EP 0331485. Preferred siliconelubricants are siloxanes available from Dow Corning under the tradenames of DC 200® FLUID. Preferably, the viscosity of such siloxanes isgreater than 50,000 est. A particularly preferred material is alsoavailable from Dow Corning under the trade name of Si Powder ResinModifiers and MB Master Batches, for instance, MB 50-320. The siloxanesare generally used in the range of 0.01 to 10 parts by weight based on100 parts total polymer, the preferred range being 0.01 to 5 parts byweight based on 100 parts total polymer.

Slip aids are used to reduce the force required to remove the closurefrom a bottle or package. There can be found in the literature examplesof the use of unsaturated amides, See e.g., JP 2002068282, U.S. Pat. No.5,929,128, JP 02191166. However, the present inventor believes that theuse of a saturated amide in a container closure or closure sealant isnew. Saturated amides which are believed suitable for use in the presentinvention include behenamide, arachidamide, stearamide, palmitamide,myristamide, and lauramide. These are commercially available from CrodaUniversal. The term “saturated” as used herein shall mean tocompositions wherein the iodine value is no greater than 10 and morepreferably no greater than 5.

Secondary saturated bis-amides are also believed to be suitable slipaids for use in the present invention. For example, ethylenebis-stearamide is commercially available as from Croda Universal underthe tradename CRODA EBS. A preferred amide for use in the presentinvention is stearamide.

Oxidized polyethylenes, with or without the saturated amide, are alsobelieved to be suitable slip aids for use in the present invention.These are commercially available from Honeywell under the tradename A-C,one particularly preferred version being named or otherwise denominated“A-C 629A.” The typical ranges of both these types of slip aides are0.01 to 8 parts based on 100 parts of the base polymer(s).

Optional components for use in the compositions and methods of theinvention include pigments, antioxidants, stabilizers, hydrocarbon oils,phthalate ester plasticizers, epoxidized soybean oil, foaming agents,acrylic processing aides, fillers, and nanocomposites. Additionallyactive packaging components may be included such as oxygen scavengers,aldehyde scavengers, anti-microbials, and flavor enhancing agents.

Exemplary compositions of the invention may be formed, such as bymolding, into beverage or food containers, closures, or closure sealantssuch as cap linings.

The present invention also provides slip aid compositions. An exemplaryslip aid composition for use in container closures and closure sealants,comprises: a silicone (e.g., a siloxane, an organosiloxane such aspoly(dimethyl)siloxane, etc.) having an average molecular weight notless than 40,000; the silicone being present in an amount not less than0.01 parts and not greater than 10 parts based on 100 parts of said basepolymer(s); and a slip aid comprising a saturated amide, an oxidizedpolyethylene, or mixture thereof; said slip aid being in an amount notless than 0.01 parts and not greater than 8 parts based on 100 parts ofsaid base polymer(s).

The foregoing embodiments and examples are provided for purposes ofillustration only and are not intended to limit the scope of theinvention. In the examples, the following abbreviations are used:

EVA Ethylene-vinyl acetate copolymer, 14% VA EP Ethylene propylenecopolymer ER Crodamide ER SR Crodamide SR EBS Crodamide EBS Si1 DowCorning 200 fluid, 60000 cst Si2 Dow Corning 200 fluid, 100000 cst Si3Dow Corning MB50-320 AO antioxidant BLUE pigment OXP OxidizedPolyethylene

EXAMPLE 1

The compositions in table 1, below were blended, extruded into films,and 1 inch discs punched out. The discs were then inserted into 28 mmpolypropylene caps designed for carbonated soft drink applications. Thecaps were then applied to 20 oz. PET bottles filled with water using acommercial application machine. The bottles were stored at roomtemperature for less than week and greater than 24 hours, after which,the force required to remove the cap was measured and any tearing,scuffing or stringing of the liner was noted.

TABLE 1 A B C D E F G EVA 90 90 90 90 90 90 90 EP 10 10 10 10 10 10 10AO 0.1 0.1 0.1 0.1 0.1 0.1 .1 BLUE 0.8 0.8 0.8 0.8 0.8 0.8 .8 ER 0 1 0 00 0 0 EBS 0 0 1.5 0 0 0 0 SR 0 0 0 1.5 0 0 0 OXP 0 0 0 0 1 0 0 Si1 0 0 00 0 1 0 Si2 0 0 0 0 0 0 0 Si3 0 0 0 0 0 0 2 Removal >23.6 10.6 >24.2 2020.6 16.7 13.2 Torque, in- lbs. Stringing/ 100% 10% 70% 80% 40% 100%100% Scuffing

As shown above, no one lubricant or slip aid alone provided the samedegree of performance as erucamide. Stringing and/or scuffing of theliner was believed be be caused from the bottle surface tearing theliner. In the food and beverage industry, this is deemed unacceptable asit can cause pack contamination. An insufficient lubrication/slipproperty on the surface of the liner will cause this to worsen.

EXAMPLE 2

In accordance with the procedure described above for Example 1, thefollowing compositions were applied to caps and tested, as shown inTable 2 below.

TABLE 2 A B C EVA 90 90 90 EP 10 10 10 AO .1 .1 .1 BLUE .8 .8 .8 Si3 3 30 Si2 0 0 1.5 SR 0 1 1 OXP 1.5 0 .5 REMOVAL 13.6 10.3 12.0 TORQUE,IN-LB. STRINGING/ 0% 0% 14% SCUFFING

This data indicates that by utilizing a mixture of siloxanes andethylenically saturated amides and/or oxidized polyethylene, incombination, provided performance equal to that of erucamide.

EXAMPLE 3

In another example, compositions similar to above were extrusion blendedand pelletized. The pellets were then melted in another extruder, andthe molten pellets were transferred directly from the extruder to theindividual cap and immediately compression-molded.

The resulting lined caps were allowed to age at room temperature for aminimum of 1 week prior to testing. The caps were then applied to 20 oz.PET bottles filled with water using a commercial application machine.The bottles were stored at 40° F. for less than week and more than 24hours. After this period, tests were performed to measure the forcerequired to remove the cap, and any tearing, scuffing or stringing ofthe liner was noted.

Compositions containing a siloxane in conjunction with an ethylenicallyunsaturated amide and/or an oxidized polyethylene slip aid gave removaltorques comparable to compositions containing erucamide. Stringing wasjudge to be commercially acceptable by industry standards. However, acomposition using a siloxane alone without an unsaturated amide and/oroxidized polyethylene gave unacceptably high removal torque andstringing.

By utilizing a mixture of siloxanes and ethylenically unsaturated amidesand/or oxidized polyethylene, in combination, performance equal to thatof erucamide was obtained by compositions of the present invention.

The foregoing embodiments and examples were provided for illustrativepurposes only and not intended to limit the scope of the invention.

I claim:
 1. A composition, comprising: (A) a matrix polymer, copolymer,or blend thereof, which is essentially free of erucamide, which isessentially free of unsaturated amide, and which is operative to providea container, container closure, or closure sealant, said matrix polymer,copolymer, or blend thereof being selected from thermoplastic polymersconsisting of polyethylene or ethylene copolymer with other loweralkenes, polypropylene, thermoplastic rubber, poly (ethylene propylene)copolymer, acid modified ethylene propylene copolymer, styrene butadienerubber, carboxylated styrene butadiene block copolymer, polyisoprene,styrene isoprene styrene block copolymer, styrene butadiene styreneblock copolymer, styrene ethylene butylene styrene block copolymer,polystyrene block polyethylene/propylene copolymer, ethylene vinylacetate copolymer or terpolmer, ethylene acrylate copolymer orterpolymer, ethylene vinyl alcohol copolymer, butyl rubber, andpoly(vinyl chloride) polymer; (B) a lubricant comprising anorganopolysiloxane, said organopolysiloxane having an average molecularweight not less than 40,000, said organosiloxane being present in saidcomposition in an amount not less than 0.01 parts and not greater than10 parts based on 100 parts of said matrix polymer, copolymer, or blendthereof which comprises said component (A), and said organopolysiloxanehaving a viscosity of at least 50.000 cst; and (C) a slip aid comprisinga saturated amide and an oxidized polyethylene, said slip aid beingpresent in said composition in an amount not less than 0.01 parts andnot greater than 8 parts based on 100 parts of said component (A), saidamide having an iodine value no greater than 5 in accordance with ASTMD2075-92; said composition when employed in a container, containerclosure, or closure sealant providing reduced off-tastes whilemaintaining slip-aid efficiency when compared to compositions containingunsaturated amide.
 2. The composition of claim 1 comprising at least twoof said thermoplastic polymers or copolymers.
 3. The composition ofclaim 1 wherein said matrix polymer, copolymer, or mixture thereofcomprises an ethylene vinyl acetate copolymer in an amount not less than5 parts and not greater than 100 parts, based on 100 parts of saidcomponent (A).
 4. The composition of claim 1 wherein said matrixpolymer, copolymer, or mixture thereof comprises polyethylene,polypropylene, or blend thereof.
 5. The composition of claim 4 whereinsaid matrix polymer, copolymer, or mixture thereof comprises a copolymerof polyethylene and polypropylene.
 6. The composition of claim 1 whereinsaid organopolysiloxane is poly(dimethyl) siloxane.
 7. The compositionof claim 1 wherein said saturated amide is selected from the groupconsisting of behenamide, stearamide, arachidamide, palmitamide,myristamide, lauramide and ethylene bis-stearamide.
 8. The compositionof claim 7, wherein said saturated amide is stearamide.
 9. Thecomposition of claim 7 wherein said saturated amide is behenamide. 10.The composition of claim 1 being molded into a beverage container. 11.The composition of claim 1 being molded into a beverage containerclosure.
 12. The composition of claim 11, wherein said beveragecontainer closure is a plastic cap.
 13. The composition of claim 1 beingmolded into a cap liner.
 14. The composition of claim 1 wherein saidmatrix polymer comprises ethylene vinyl acetate copolymer, and furthercomprises poly(ethylene propylene copolymer).
 15. The composition ofclaim 1 wherein said ethylene vinyl acetate copolymer or terpolymer andsaid poly(ethylene propylene) copolymer constitute 100% of said matrixpolymer.
 16. The composition of claim 14 wherein said saturated amide isstearamide.
 17. The composition of claim 16 wherein saidorganopolysiloxane is poly(dimethyl)siloxane.
 18. The composition ofclaim 1 wherein said matrix polymer comprises poly(vinyl chloride)polymer.
 19. The composition of claim 18 wherein said poly(vinylchloride) polymer constitutes 100% of said matrix polymer.
 20. Thecomposition of claim 1 wherein said matrix polymer comprisespolyethylene, polypropylene, or mixture thereof; and said matrix polymerfurther comprises styrene ethylene butylene styrene block copolymer.